2000 Miata p0300 code

After 15 minutes of driving my 2000 Miata, which I recently purchased with 18K miles on it, I parked it for a half hour and then came to leave. It started but began to run roughly and the CL came on. We continued driving with it running poorly and after about a mile, it cleared. I put the OBDII on it and got a P0300...hah! Says..."Multiple misfire detected". It felt like at least 2 cyl were off, Has new wires and Bosch platinum plugs. This has occurred at least 3 times under same kind of circumstances. Most of the time, it runs fine. Any suggestions on how to isolate specific problem? Thanks much.

I have the same problem with my 2000 Mitia. It has also happened three times and seems to be heat related. The last time that it happened I sprayed water on the coil/ignitor while the engine was misfiring and the misfires quit after about 10 seconds. I will do this again the next time it happens to confirm that the coil/ignitor is the failing component.
I had a similar problem on a 86 Sable, but it would quit completely for about an hour before I could restart the engine. The next time it quit I sprayed water on the base of the distributor where the ignitor was located and the car started immediately. I replaced the ignitor and the problem was fixed.

Thanks for the response. I presume that you are calling the coil pack 'the ignitor'? Is that right? I took it out the other day and ran it hard. The result was for the CL to come on with a code 0421 and it would not maintain an idle. It is really starting to bug me since it is like new. Spraying water sounds good for cooling down but also sounds like a source for electrical arcing; no?

Thanks for the response. I presume that you are calling the coil pack 'the ignitor'? Is that right? I took it out the other day and ran it hard. The result was for the CL to come on with a code 0421 and it would not maintain an idle. It is really starting to bug me since it is like new. Spraying water sounds good for cooling down but also sounds like a source for electrical arcing; no?

Yes, I've seen it listed for sale on the other web sites as "coil ignitor" or "coil with ignitor".
I assume there is some solid state electronics in this assembly.
The insulation of the of this assembly should be good enough to keep it from arcing. I didn't have any problem when I sprayed mine with water.
After my previous post I found another forum with a lot of info on this problem. http://forum.miata.net/vb/archive/index.php/t-127238.html

Thanks again. These ignition packs seem to be soft spot for the 99-2000 series. The link that you provided is VERY good. It sure is starting to sound like the coil pack as I have most of the codes and symtoms that they are describing. It's really difficult to isolate these problems and the dealers aren't much help when it is 'intermittent'.